DESCRIPTION: The strong association between mental stress and morbid cardiovascular events in coronary artery disease (CAD) patients may derive from stress-induced cardiac ischemia due to exaggerated increases in vascular resistance and arterial pressure. In fact, this may explain part of the prognostic relationship of baroreflex cardiac vagal control to cardiovascular outcome among CAD patients. The hemodynamic responses to psychological stress are buffered by the arterial baroreflex; thus, exaggerated pressor responses to mental stress may result from impaired baroreflex regulation in CAD patients. The specific aims of this proposal are: 1) to characterize relationships between vascular stiffness and baroreflex regulation among CAD patients, also contrasting healthy control subjects with CAD patients; 2) to examine, in relation to individual differences in pharmacologically derived estimates of baroreflex function, changes in autonomic and baroreflex control during laboratory psychological stress among CAD patients and among healthy control subjects; 3) to test the hypothesis that impaired baroreflex regulation in CAD patients, due to increased vascular stiffness and/or attenuated autonomic control, is associated with exacerbated hemodynamic reactions to psychological stress. Bolus vasoactive drug infusions in combination with Finapres beat-by-beat arterial pressures and carotid B-mode ultrasonography will be used to evaluate baroreflex sensitivity and arterial stiffness. Baroreflex adjustments to psychological stress will be assessed by power spectral-derived relations between arterial pressure and cardiac chronotropy during a mental arithmetic task and a speech task. The degree to which indices of baroreflex function are associated with hemodynamic responses to psychological stress among CAD patients will be assessed. There are no data which related carotid or aortic stiffness to cardiovascular control during mental stress in healthy or CAD populations. Thus, this research may provide unique insight to the mechanism and psycho-physiological correlates of reduced baroreflex sensitivity in CAD patients.